Low power and Lossy Networks (LLNs), e.g., sensor networks, have a myriad of applications, such as Smart Grid Advanced Metering Infrastructure (AMI) and Smart Cities. Various challenges are presented with LLNs, such as lossy links, low bandwidth, battery operation, low memory and/or processing capability, etc. One example routing solution to LLN challenges is a protocol called Routing Protocol for LLNs or “RPL,” which is a distance vector routing protocol that builds a Destination Oriented Directed Acyclic Graph (DODAG, or simply DAG) in addition to a set of features to bound the control traffic, support local (and slow) repair, etc. The RPL architecture provides a flexible method by which each node performs DODAG discovery, construction, and maintenance.
Some LLN deployments, such as Smart Grid AMI deployments, may include upwards of millions of LLN nodes/devices. To account for the typically constrained nature of the various devices, mesh technologies (e.g., CG-Mesh, RFLAN, etc.) often divide the deployed devices into smaller sets, with each being serviced by a border router. Thus, the mesh network may be divided into any number of PANs, each PAN having a border router providing inter-PAN connectivity to the nodes in its local PAN.
PAN formation may be optimized based on various network metrics. For example, a node may join a given PAN based on the link metrics between itself and its neighbors (e.g., signal strength, packet loss, etc.), the overall path cost between itself and the border router, or other such factors. Accordingly, an LLN node typically favors joining a PAN that has fewer nodes, thereby reducing the overall path cost between the node and the border router of the PAN.